A comprehensive study of the etiological relationship of bacterial and non-bacterial agents to infectious complications of delivery and puerperium is undertaken. The study will focus especially upon the isolation of mycoplasmata (Mycoplasma hominis and T-strains) and bacteria from a study group composed of women having cesarean section, but also women undergoing vaginal delivery and women with gynecological surgery unrelated to pregnancy, will be included. Attempts will be made to isolate mycoplasmata and bacteria from blood of all patients, uterine cavity and fallopian tubes of patients from whom specimens can be obtained at the time of operation without the possibility of vaginal contamination and from the cervix. Antibody response to mycoplasmata and chlamydiae will be determined on all patients. The findings of fever in relation to parturition, duration at ruptured membranes, history of pelvic inflammatory disease or other gynecological disorders will be related to the laboratory results. A follow-up of gynecological disorders and the reproductive experience of the study patients is planned to obtain further history of possibly related disease syndromes and fertility.